| 摘要 |
PURPOSE: To efficiently purify hydrocarbon HC in exhaust gas at the time of cold starting of an engine, without lowering output performance of the engine, in regard to a device controlling emission from the engine. CONSTITUTION: A catalyst device 20 is provided, which comprises an HC adsorbent 2a adsorbing HC in the exhaust gas, an HC purifying catalyst 2b capable of purifying the HC separated from the HC adsorbent 2a, and transition metal 5 adsorbing CO in the exhaust gas. An HC desorption timing estimating means 6 estimates timing that the HC separated from the HC adsorbent. By a controlling means 7, an air/fuel ratio is made to be richer than a stiochiometric air/fuel ratio at the time of starting an engine 30, thereby starting driving. The air/fuel ratio is switched to lean according to the desorption timing of the HC based on output of the HC desorption timing estimating means 6.
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